Effect of Solution Treatment on High Temperature Creep Behavior of Incoloy 800H
Incoloy alloy 800H is solution strengthened Iron-Nickel-Chromium (Fe-Ni-Cr) superalloy with good strength and excellent resistance to oxidation and carburization for high temperature applications such as nuclear reactors, gas turbines and heat-treating industries. Hence, high temperature creep property becomes an important aspect to be considered during material selection for such applications. The primary objective of this paper is to study the effect of microstructural variation of Incoloy 800H on the high temperature creep properties. The materials were heat treated at temperature 900°C, 1050°C, 1150°C and 1200°C for 3 hours and followed by water quench. The grain sizes varied from 94.28 to 380.95 µm after the solution treatment at various temperatures. High temperature creep tests were performed on the heat-treated samples at temperature 800°C with constant stress of 100 MPa. The creep curves results show primary, secondary and tertiary stages. The 800H alloy shows an increase in steady state creep rate with increase in grain size of the solution treated sample. The samples after creep tests were analyzed using optical microscope, scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and transmission electron microscope (TEM). Recrystallizations of the grains were also observed near the fracture surface and it was also found that the samples failed in ductile mode with cavitation at the grain boundaries.
Keywords- Incoloy 800H, High Temperature Creep, Superalloy.